Drain

In medicine, to remove fluid as it collects; or, a tube or wick-like device used to remove fluid from a body cavity, wound, or infected area.

A vertical well or borehole, usually downstream of impervious cores, grout curtains, or cutoffs, designed to collect and direct seepate through or under a dam to reduce uplift pressure under or within a dam. A line of such wells forms a drainage curtain. May also refer to a small valve and conduit that is used to evacuate an outlet pipe, stilling basin, or reservoir pool. See also, "Relief Well".